High-Performance HMI Design Basics

We are going to dive a little deeper and discuss the Fundamentals of High-Performance HMI Design.
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Welcome back, in our previous article, What is High-Performance HMI?, we discussed the state of most current HMIs, their drawbacks, and design flaws. We then covered why a High-Performance HMI is becoming the standard for processes around the world, and some basic concepts for developing a High-Performance HMI. In this article, we are going to dive a little deeper and discuss the Fundamentals of High-Performance HMI Design, High-Performance HMI Standards, along with best practices.

The intended user of HMI

One very important fundamental of HMI design is the intended user of the HMI. There is a common misperception that an HMI should be designed to accommodate several different users, including supervisors, engineers, maintenance personnel, and finally, the operators. This is simply not true.

An HMI is meant to be designed around the needs and the workflow of an operator. Other personnel will have an interest in the information displayed on an HMI, but those interests are not common, and usually come into play when the plant is in an abnormal situation.

An HMI designed around the requirements of the operators will give them the ability to quickly point out any abnormalities or devices that need to be diagnosed, without an engineer or maintenance person fumbling around through screens looking for the problem.

This is why it is crucial for operator workshops in the development phase of the HMI. They can provide much-needed input to you, the controls engineer when designing a High-Performance HMI.

Intended User of HMI

HMI philosophy document

The fundamental part of the workshop process is developing the HMI Philosophy Document and Style Guide. To put it simply, the HMI Philosophy Document will lay the groundwork for engineers and owners to design the HMI for the process that they have been tasked to build.

It is meant to provide guidance in situations where there are multiple control systems in a single site to retain continuity across the various control systems.

In a greenfield project, the HMI Philosophy Document will be relatively easy to develop as there is not an existing HMI that operations have become used to working with. This will not necessarily be the case in an application where an existing HMI will be overhauled.

You will probably encounter a lot of resistance, so this is where your wisdom and thorough knowledge of what a High-Performance HMI is, will be an essential item in your toolbox. This means getting the buy-in from all stakeholders to make your project a success. Without the support of these stakeholders, your project may be doomed before you even start.

HMI Philosophy Document

HMI style guide

Once you have your HMI Philosophy Document, it is time to develop the HMI Style Guide. The style guide is a much more detailed document that is based on the framework from the Philosophy Guide.

This document is where every aspect of the proposed HMI is covered. You will get down the granular detail of the screen layout, the color of backgrounds, line types and thickness, text size and font, and ISA objects for pumps, valves, and tanks.

It will also cover how trends are to be displayed and how the navigation from one screen to another will be handled. The style guide is specific to a project and its specific control system and hardware configuration.

By having all of this information now, you will know that the project you develop will maximize the control system capabilities and still work within the constraints of its limitations. Again, this hard work upfront will make your project easier and lead to a much better chance of success and of course, profits.

When you develop your HMI Style Guide, it will become your roadmap to success. A good HMI Style Guide will be a living document while it is in development. This means that a management of change process should be a part of developing the Style Guide.

When a section is updated, there should be quality control and approval process in place. On final approval, the HMI Style Guide is your blueprint to building your High-Performance HMI, giving clear instruction to the development of your High-Performance HMI project.

HMI Style Guide line

Guideline for object library in HMI design

A Style Guide will document the screen objects that you will use when creating your displays. The objects along with their source code will become the control system specific object library for the project. These objects are then automatically standardized and will each have specific functions in the control system.

When developing the object library, the objects should not be individually modified during the development of individual displays. Instead, objects are global and are available for use across all displays for a standardized method of displaying information from field devices.

Your HMI Object Library or HMI Template Suite will become the predefined repository of source code such as add on instructions, display objects and faceplates that will enable you to quickly develop the project using tested strategies, high functionality, and known performance.

Objects will be built with the design standards set forth in your HMI Style guide, along with consideration given to ISA101 High-Performance HMI standards.

Guideline for Object Library in HMI

Benefits of using object library in HMI design

The object library will allow you to create a control system using a drag and drop environment in order to quickly create a control function.

For example, an analog input object will have predefined scaling, alarms and engineering units, among many other features. Then the corresponding faceplate will give the operator an intuitive and information-driven visibility and control.

By using this modular design, you are able to access a large number of small components that will make up an overall control system. This method of development leads to a reduced chance for error, reduction in development time and cost, and increased profitability.

Remember, offsite backups of your library are essential. There have been many horror stories of an object library being lost because it was stored on a single laptop computer hard drive.

Benefits of using object library in HMI

We hope you enjoyed the second part of our series on High-Performance HMI. This series is meant to give you the foundation of knowledge to begin creating High-Performance HMI projects.

We recommend checking the following related articles, if you haven’t already, to have a better understanding of High-Performance HMI Philosophy:

What is High-Performance HMI? (Part 1 of 4)

▶ High-Performance HMI Design Basics (Part 2 of 4)

Development of High-Performance HMI Philosophy (Part 3 of 4)

Detailed Design Principles of High-Performance HMI Display (Part 4 of 4)

If you have any questions about High-Performance HMI and HMI Design standards, add them in the comments below and we will get back to you in less than 24 hours.

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